Well it's your country and you vote for the laws you want I suppose.
It's not always just that. In the cases outlined, the Supreme Court ruled that involuntary confinement under other than the circumstances listed was unconstitutional. So one could vote for any sort of laws that contravened that; they'd be struck down.
But consider this. Let's say you come here to visit. You go to a local bar with some friends and things get out of hand, and you eventually come into contact with the local police. They arrest you but furthermore, they believe there is something about your behavior that leads them to believe you might just be a dangerous lunatic as well.
So they put you on a 72-hour psych hold and you get locked up until evaluated by psychiatrists. Now, as we all know, you're absolutely sane. But let's just say that the shrinks don't care for your test results and due to that, they convince a judge to keep you locked up somewhat longer. You're outraged, of course, but what can you do?
Eventually, they decide they've fixed you enough to let you out on your own, but they give you prescriptions for various drugs and make appointments for you with therapists who will supposedly make you better.
Since you know that you're not insane, but clearly someone is doing something very very wrong, do you take the drugs, go to the counselling, or do you say to hell with that and get out of that town as fast as you can?
Right you are, time to beat feet for the border.
Now consider that crazy people do not believe they are crazy.
And that's how they react. As an innocent man would.
So they don't take the drugs, and they don't go to the appointments.
And unless they have demonstrated that they're dangerous to themselves or others, they're left to their own devices.
If we're going to give people the authority to lock people up for being nuts and compel them to take medication and see therapists, we might want to be certain that we don't get any false positives. Or is it OK to lock up a few sane men just so we get the truly crazy ones off the street?